Lamentably but perhaps inevitably, the mayoral race pits two San Diegos against each other.

In the nasty, brutish and short stretch run, pro-business GOP and pro-union Democratic machines wield glossy mailers, robocalls and TV ads to inflame fault lines of class and ethnicity, mocking the reconciliation of the two San Diegos.

In the municipal mortification department, the run-up to the Bob Filner resignation is rivaled only by the closing moments of the runoff to replace him.

What a turnoff this cartoonish finale is to a typical independent voter, exhausted by mailers sending lurid, barely subliminal messages:

KEVIN FAULCONER HOBNOBS AT THE SAN DIEGO YACHT CLUB! DAVID ALVAREZ IS JUST 33 AND HE LOOKS GANGSTA FLASHING CASH! FAULCONER WANTS TO BURN FIREFIGHTER DISABILITY BENEFITS! ALVAREZ WILL ROB CARMEL VALLEY TO SHOWER TAX DOLLARS ON SAN YSIDRO!

Whatever sense the two even-keeled councilmen have made in debates has been hijacked by closing arguments that make both candidates look like prisoners of war.

Surveying the no-sane-man’s-land, my compass turns to the city’s north and south poles, both relatively recent transplants on the body politic.

Rancho Bernardo, a master-planned paradise for Midwestern retirees, was annexed by the city in the early ‘60s. The RB Republican registration advantage over Democrats is more than 30 percent, according to the Registrar of Voters. The disparity in activism is even greater.

“Tea Party meetings in RB typically draw 50 people, but last month only 10 people attended RB’s Democratic Club,” says Marty Judge, vice president of the RB-based Conservative Order of Good Government, an influential group.

If Faulconer is to win the last-ditch turnout war, RB will be a deep pocket of conservative, anti-union votes.

In 1957, San Diego staked out a narrow corridor of land on the floor of the bay to annex the noncontiguous border communities of San Ysidro, Nestor and Otay Mesa. In this largely Latino community, the Democratic advantage over Republicans is dramatic: 60 percent.

This week, I drove to the Montgomery-Waller Park, reputed Otay Mesa site of the first U.S. manned flight.

A Latino gentleman out for a morning walk helped me identify Nestor in the valley below. I wondered aloud if the vast majority of those households would turn out for the first Latino mayor in the city’s history.

“I’ve already mailed in my vote,” he said with a broad smile that left no doubt as to whom he voted for.

Suspended between the city’s north and south poles, the next mayor will take office not a moment too soon.